The amount of salt on the menus of the six biggest fast food companies varies greatly from nation to nation, according to a study Monday that calls for regulations to curb sodium intake.

The amount of salt on the menus of the six biggest fast food companies varies greatly from nation to nation, according to a study Monday that calls for regulations to curb sodium intake.

"We saw marked variability in the reported salt content of products provided by major transnational fast food companies," said Norman Campbell, lead author of the study published in the Canadian Medical Association Journal.

Researchers in Australia, Britain, Canada, France, New Zealand and the United States looked at the salt content of 2,124 food items sold by Burger King (known as Hungry Jack's in Australia), Domino's Pizza, Kentucky Fried Chicken, McDonald's, Pizza Hut and Subway.

These included popular items such burgers, chicken nuggets, pizza, salad, sandwiches and fries.

Fast food in Canada and the United States contained much higher levels of sodium than in Britain and France, they found.

In Canada, McDonald's Chicken McNuggets, for example, contained two and a half times the amount of sodium per serving than in Britain.

Too much dietary salt has been linked to higher blood pressure and other adverse health effects. Other studies have shown cuts in salt intake can result in a significant reduction in deaths.

Several countries have started to curb salt intake, with the latest successes coming from voluntary salt reduction targets and labeling of foods.

However, food companies often cite technical food processing issues as barriers to further reducing salt content, stating that new technology and processes are needed to make lower-salt products.

The study shows this to be false and that decreasing salt in fast foods is in fact technically feasible, said Campbell.

The University of Calgary professor went on to say that "voluntary efforts aren't working." "These high levels indicate failure of the current government approach that leaves salt reduction solely in the hands of industry."

"Salt reduction programs need to guide industry and oversee it with targets and timelines for foods, monitoring and evaluation, and stronger regulatory measures if the structured voluntary efforts are not effective," he concluded.